In recent years, regulations to hydrocarbon transpiration gases from vehicular fuels have been greatly tightened particularly in the United States. In response to such regulations, advances are being made in the development of rubber hoses for fuels.
In particular, multi-layered fuel hoses have been proposed. Such a multi-layer structure includes an intermediate layer having a resin material provided as a fuel barrier, and inner and outer layers having rubber materials laminated on both sides of the intermediate layer. This structure provides connection-pipe sealing, fuel impermeability, and flexibility.
A fuel hose has been proposed that has fluorine-contained rubber (FKM) or acrylonitrile-butadiene rubber (NBR) provided as an inner layer, a ternary copolymer fluororesin THV (tetrafluoroethylene-hexafluoropropylene-vinylidenefluoride) with a fuel barrier function provided as an intermediate layer, and epichlorohydrin rubber (ECO) or nitrile rubber (acrylonitrile-butadiene rubber, NBR) provided as an outer layer. Further, a fuel hose having a layer of chlorosulfonated polyethylene rubber (CSM) or chlorinated polyethylene rubber (CPE) laminated on an outer layer of the fuel hose has been proposed (refer to Patent Document 1).